With over 1.5 million persons suffering head injury annually in the U.S., and approximately 50,000 dying from these injuries, a need exists for early direct assessment of brain injury. Currently, injuries must be inferred from Glascow Coma Scores (GCS), low blood pressure, and/or low pulse oximetry, but there is no direct method of measuring brain condition at the scene. Active Signal proposes to test a small, portable, hand-held device to perform non-invasive measurements of brain injury, allowing direct assessment of injury even with lack of patient responsiveness. Thus, brain injury will be distinguished from low CGS caused by drugs, alcohol and hypoglycemia, and the information used for triaging and even early intervention. The brain trauma assessment system (BTAS) is modeled on one that has successfully identified neurological status on >150 trauma patients at the University of Maryland Shock Trauma Center (STC). Here, EMTs will use the BTAS on patients at the scene of injury and during transport. The measurements will be compared to the diagnosis upon admission to the STC to evaluate the device's sensitivity and specificity. Active Signal will make adjustments to accommodate demands of the EMS environment in preparation for a broad study in Phase II.